1&rpar;Two digit display deisgn&comma; the display with Chrome metal front cover&period; 2&rpar;Two&comma; four or six sensors for option3&rpar;English voice box is optional4&rpar;Classical circuit design to make sure the product has strong anti-interference from car engine and current impulse&period; It avoids false alarm happening5&rpar;There is Switch behind the display which is used to turn on and off buzzer or human voice&period;